How much solar energy can Ontario homes use?

How good is Ontario's solar resource?

Southern Ontario sits at a latitude similar to much of the northern United States and gets a solid summer sun, with long days and strong midday light. Winters bring short days, low sun and frequent cloud, particularly near the Great Lakes. Output is therefore uneven through the year. The measure installers use is peak sun hours, which we explain in peak sun hours across Canada.

The province is not the same everywhere. Lake-effect cloud and snow, urban shading and local weather make a difference even within one region, which is why a model built for your address matters.

For a home, the practical question is simple: does your own roof see the sun for most of the day? A roof that is clear from about nine in the morning to three in the afternoon is usually a good candidate, and a site visit will confirm it.

How does output change through the year?

A fixed rooftop array produces most in late spring and summer and least in December and January. Cold, clear days can help panel efficiency, while snow cover and short days limit what is collected. Solar panels in winter and snow removal on solar panels explain what to expect and what not to attempt on a roof.

This seasonal swing is also why credits for surplus summer power matter. A system sized to your annual use can overproduce in summer and underproduce in winter, with the balance handled by the grid and your utility's credit rules.

What shapes how much energy a system gives you?

Several factors do the work.

• Roof direction and tilt. South-facing, tilted at about the latitude, collects most, as set out in the best solar panel direction guide.
• Shading. Trees, chimneys and neighbouring buildings can cut output sharply.
• Equipment. Panel efficiency and the inverter change the result, as solar panel efficiency in Canada explains.
• System size. The number of panels, relative to your use, sets how much of your bill is offset.

How do you turn sunshine into savings?

Energy produced only saves money when it replaces power you would buy or earns credits. In Ontario that depends on net metering, your electricity rate plan and the local distribution company. These rules change, so check the current terms with the Ontario Energy Board, the provincial energy ministry and your utility. Our guide to how many panels a house needs shows how to size a system, and reading a production estimate shows how to test an installer's claim.

Solar heat is a related use of the same sun. At Drake Landing in Alberta, collectors stored summer heat in the ground for winter, described on the how it works page.

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